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    AnatomyA

    Anagen Phase

    /AN-uh-jen/

    Definition

    The active growth phase of the hair cycle, during which the hair follicle is producing new hair. Laser hair removal only works on hairs in this phase.

    The anagen phase is the first and longest stage of the hair growth cycle. During anagen, cells in the hair follicle's matrix rapidly divide, pushing the hair shaft upward and producing new visible hair growth. This is the only phase during which the hair contains enough melanin in the follicle for laser energy to effectively target and damage it.

    The Three Hair Growth Phases

    • Anagen (active growth): Lasts 2–7 years on the scalp; weeks to months on body hair. Roughly 20–30% of body hair is in this phase at any time
    • Catagen (transition): Hair detaches from blood supply; lasts 2–3 weeks. The follicle shrinks
    • Telogen (resting): Hair sheds naturally; lasts 2–4 months. A new anagen hair begins growing beneath it
    ℹ️ Good to KnowThis is why laser hair removal requires 6–8 sessions — each session targets the 20–30% of hairs currently in anagen. Spacing sessions 4–6 weeks apart ensures you catch the next batch entering active growth.

    Related Terms

    Laser Hair Removal

    A medical procedure that uses concentrated light beams to target and destroy hair follicles, resulting in long-term hair reduction.

    Melanin

    The natural pigment produced by melanocytes that determines skin, hair, and eye color. Also the target for laser hair removal and pigmentation treatments.

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